Ischaemia

Question 1

what is the most common reason to perform an ECG?

Answer 1

to evaluate patients with known or possible CAD

Question 2

T/F a normal ECG excludes CAD

Answer 2

false - normal ECG doesn’t exclude CAD, even with widespread disease

Question 3

What are the general rules of ECG interpretation for ischaemia/ infarction

Answer 3

• must known pt Hx
• focus on ST, T wave changes and q waves
• always look at old ECGs if available
• do serial ECGs in borderline STEMI cases or if recurrent symptoms
• always do a second ECG (12 hour or day 2) in ACS patients
• ECG when in pain a priority

Question 4

ECG changes may indicate a particular vascular territory e.g. ST elevation in the anterior chest leads is most likely due to which artery being occluded?

Answer 4

LAD

Question 5

state which ECG leads relate to which ECG territories

Answer 5

lateral: I, aVL, V5, V6
inferior: II, III, aVF
anterior: V1 - 4

Question 6

What T waves changes may be seen as a marker of ischaemia

Answer 6

• tall
• biphasic
• inverted
• flattened

Question 7

How can ST depression be prognostic as a marker of ischaemia?

Answer 7

may be subtle in less severe disease.

Widespread and deep ST depression = bad disease!

Question 8

What is the ECG criteria required for thrombolysis?

Answer 8

• ST elevation
• > 1mm in two contiguous limb leads
• > 2mm in two contiguous chest leads

Question 9

eventually, ST segment elevation may become so pronounced that there is loss of R wave and formation of __ wave

Answer 9

Q

Question 10

Q waves in infarction are generally accompanied by loss of __ wave height. They develop between __ and __ hours. What does their presence indicate?

Answer 10

• Q
• 2 - 24
• suggest myocardial necrosis and loss of viable myocardium

Question 11

T/F: Q waves always = completed infarct or blocked artery

Answer 11

not always

Question 12

what is the definition of a pathological q wave

Answer 12

• any Q wave in V1-3
• Q wave ≥ 0.03s in I, II, aVL, aVF, V4, V5 or V6
• must be present in any two contiguous leads and be >1mm in depth

Question 13

Why is it important to identify ST changes on an ECG?

Answer 13

early identification and treatment of ST segment elevation improves prognosis

Question 14

What are some other causes of ST segment elevation other than MI?

Answer 14

• benign early repolarisation
• LBBB
• LVH
• ventricular aneurysm
• coronary vasospasm/ Printzmental’s angina
• Pericaditis
• Brugada syndrome
• SAH

Question 15

In patients with NEW LBBB, what diagnosis should be considered

Answer 15

acute MI

Question 16

T/F: all pts with LBBB should be thromolysed

Answer 16

false

• is common in well people esp elderly HTN pts
• unless they look like they’re having an MI don’t thrombolyse
• cath lab is an excellent alternative option

Question 17

What criteria can be used to diagnose a STEMI in the presence of LBBB

Answer 17

Sgarbossa criteria

• see notes
• 90% specificity for detecting MI

Question 18

In patients with posterior MI, what ST changes are seen in V1-3

Answer 18

ST segment depression in V1-3